[Bug libstdc++/57641] std::timed_mutex.try_lock_until() is broken

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57641

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-18
     Ever confirmed|0                           |1

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The timed mutex requirements [thread.timedmutex.requirements] say:

The expression m.try_lock_until(abs_time) shall be well-formed and have the
following semantics:
Requires: If m is of type std::timed_mutex, the calling thread does not own the
mutex.

Anyway, confirming as there's a bug here relating to clocks with different
epochs, but it's easy enough to fix, I can look into it.  The same problem
exists with the private mutex type defined in std::shared_mutex